OK, thank you both. I will have anther look on Monday. David.
On Jul 11, 5:22 pm, Robert Bradshaw <[EMAIL PROTECTED]> wrote: > On Jul 11, 2008, at 7:19 AM, David Bate wrote: > > > > > Hello, > > I am a beginner to sage-devel, but I have done a search and nothing > > like this came up, although I believe it should be a newbie question. > > > I have a class, my_class say derived from float, that I want to put > > into sage so that one can type 3*my_instance on the command prompt and > > something sensible will happen. However, rather than looking for > > __mul__ in type sage.rings.integer.Integer, noticing that it doesn't > > work for my_class and then trying __rmul__ in my_class (which from my > > knowledge of python I would expect to happen) it appears sage casts > > my_instance to a float and tries the multiplication that way. > > > To solve this I tried to write a wrapper for > > sage.rings.integer.Integer.__mul__ however I get the error "can't set > > attributes of built-in/extension type 'sage.rings.integer.Integer'" > > when executing > > sage: sage.rings.integer.Integer.__mul__ = my_new_multiplication > > > Could someone enlighten me about either problem, and a possible way to > > fix it. > > > Thanks, > > David. > > This will only work for Python instances. sage.rings.integer.Integer > is an extension class, just like the builtin Python int, and the > error is similar: > > sage: int.__mul__ = my_new_multiplication > ------------------------------------------------------------ > Traceback (most recent call last): > File "<ipython console>", line 1, in <module> > TypeError: can't set attributes of built-in/extension type 'int' > > Also, note that sage.rings.integer.Integer itself is highly optimized > with lots of hacks (since its such basic type) so trying to extend it > may be difficult. > > - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
